Many gardeners add Epsom Salts to their plants and soil, often without a soil test to indicate whether or not they are really needed. I would suggest you have your soil tested. If your soil test indicates adequate soil levels of magnesium, adding more will upset the soil chemistry enough that calcium could be unavailable to the pepper plants. SulPoMag is a naturally occurring mineral containing significant quantities of sulfur, potash, and magnesium (potassium (22%) and sulfur (22%) with 11% magnesium), for use on low-magnesium soils. Again, I'd recommend a soil test before adding anything to the soil.